I was invited to a Star Wars themed costume party so I had to improvise a costume on the fly, I had only one evening to make something... But what? I had a nice blue plastic trash can and I had already thought once that it's cover looked like an astronaut's helmet. So I decided to turn it to R2D2 spherical top!

Supplies

A blue plastic trash can

Duct tape - white and blue

A convex mirror

Bicycle lights

Electronic bicycle bell

A piece of foam plastic

An old baseball cap

Step 1: Fixing the Lid and Gluing a Baseball Cap Inside

First of all I fixed the trash can cover lid inside the cover with duct tape so that only some 5 millimeter slot remained open (I will see through it) and glued some old baseball cap without the visor in order to put it on my head.

Step 2: Covering the Helmet With White Duct Tape

Then I covered the surface of the trash can cover (already R2D2 helmet!) with stripes of white duct tape to form the pattern we see on the R2D2's head.

Step 3: Adding Some Robotic Little Things

Now I had to add some robotic stuff to make the helmet look like a real R2D2. It must not be exactly what R2D2 has on its head but it should add some R2D2ish impression to it... So I glued to the helmet a piece of a foam plastic wrapped in blue duct tape, a convex mirror on that piece of plastic, red and white bicycle lights (I know that R2D2 doesn't have bicycle lights but they blink very robotically!), an electronic bicycle bell because it produces very robotic sounds and other small stuff.